With work now starting on the blueprint for the first batch of "charter" schools, the scene would seem set for a ding-dong battle as opponents try to mobilise the only weapon they have to halt or at least delay the concept becoming reality - public opinion.

The trial of two or more such schools - an Act-driven initiative which has National's tacit blessing - could herald the most significant change in compulsory education since the Tomorrow's Schools reforms of the late 1980s and the introduction of NCEA a decade or so later.

The emphasis should be on "could". The pilot schools are not expected to open until the first term of 2014. That leaves around nine months before that year's general election - too short a period for any meaningful evaluation of the trial in lifting the educational achievements of the disadvantaged pupils the new schools will be targeting.

A re-elected National Government would therefore probably let the trial continue, opening the way to more such schools being established down the track.

A Labour-Green government would probably dump the project.

So the stakes are high, both for the teacher unions, which see the autonomy charter schools will enjoy in curriculum, classroom hours, term dates and paying teachers according to performance as the thin end of a thick wedge, and for Act, for whom charter schools are a core part of its ideology.

What has passed for debate has been conducted from those two political extremes. Unlike an issue such as paid parental leave, there seems to be little room or appetite for compromise.

Opponents of charter schools have already called in the heavy artillery in the form of a 101-page report produced by a clutch of Massey University education academics who have assessed the success or otherwise of overseas examples of charter schools.

The report might have been a valuable contribution to the debate. But any claim to objectivity was undermined by the authors' obvious disdain for charter schools, which many on the left see as an abdication of the state's responsibility to provide adequate schooling and a sell-out to profit-driven corporates.

With John Banks on the other side of the argument in his role as Associate Education Minister, you might have expected a suitably withering response. Something along the lines that the "long tail of under-achievement" in traditional state schools is testimony to those schools failing to do the job they were set up to do - provide an education that gives students from deprived areas a way to escape their backgrounds.

You would be wrong. Banks is avoiding giving oxygen to the likes of the Massey group and its pre-emptive strike on Act policy. Sometimes the best way to disarm your critics is to agree with them - and then carry on what you were doing regardless.

Such a softly-softly approach looks like being the modus operandi of Catherine Isaac, former Act Party president, wife of the Business Roundtable's Roger Kerr who died last year, and now chairwoman of the Government-appointed working group which is designing the charter schools model.

Her hug-your-enemy strategy was much to the fore in her presentation on charter schools to Act's annual conference last weekend.

She talked of the working group being open and transparent. The teacher unions would have been invited to meet its members who would be consulting widely.

Isaac, whose day job is in public relations, has shrewdly worked out that Act has nothing to gain from engaging in a slanging match with the education establishment - be it the unions, academia or the bureaucracy.

The working group, which is finalising its terms of reference, holds all the cards for now. But the long-term durability of the policy hinges on the public buying into it.

That is more likely if Isaac and Banks take the moral high ground and look inclusive, constructive and responsive to suggestions, rather than being wedded to fixed ideas.

To that end, Isaac has acknowledged faults in some overseas models of charter schools, saying it is to New Zealand's advantage that it can avoid making the same mistakes.

Above all, she has stressed that charter schools are not a "silver bullet' in terms of remedying the educational under-achievement of all children from lower socio-economic areas.

What she hoped was that charter schools would make a positive difference for some disadvantaged children.

The New Zealand schools may well follow the American "KIPP" (Knowledge is Power Programme) which sets strict criteria such as a longer school day, with pupils being expected to wear school uniform and do set homework supervised by parents.

Somewhat reluctantly, the Massey University report acknowledged that students enrolled in KIPP schools tend to perform better than similar students in traditional state schools.

But the report put this down to a high attrition rate among low-performing students and substantial extra funding of pupils.

The report concludes that the "most generous" interpretation that can be put on results is that KIPP schools reduce the achievement "gap" but do not eliminate it.

For some advocates of charter schools, the Massey report's underlying political polemic must be extremely frustrating.

Isaac's working group, however, held out the olive branch. It welcomed the report's release, pointing to areas of agreement such as the need for charter schools to have fair enrolment policies so they do not cream off the best students from other schools.

Such placatory tactics may not persuade the 30 per cent of respondents in a recent TVNZ poll who opposed charter schools to change their minds.

But being the epitome of reasonableness might tempt a chunk of the 36 per cent who professed not to know what charter schools were to line up alongside the 22 per cent who already back their introduction.

Beneath the niceties, this is an intense and not-so-friendly battle for hearts and minds. Banks and Isaac may hold the advantage for now by virtue of being in office.

Swaying public opinion to the extent necessary for the concept of charter schools to survive a change of government is a very tall order. But it is not one the Act pair will shy away from.

Herald political correspondent John Armstrong has been covering politics at a national level for nearly 30 years.
Based in the Press Gallery at Parliament in Wellington, John has worked for the Herald since 1987.
John was named Best Columnist at the 2013 Canon Media Awards and was a previous winner of Qantas media awards as best political columnist.
Prior to joining the Herald, John worked at Parliament for the New Zealand Press Association. A graduate of Canterbury University's journalism school, John began his career in journalism in 1981 on the Christchurch Star. John has a Masters of Arts degree in political science from Canterbury.